Manganese, gallium, iron magnetic alloy and method of producing particular crystal structure thereof



Sept. 21, 1965 T. A. BITHER, JR 3, 07, 33

MANGANESE, GALLIUM, IRON MAGNETIC ALLOY AND METHOD OF PRODUCING PARTICULAR CRYSTAL STRUCTURE THEREOF Filed NOV. 22, 1963 5 Sheets-Sheet l e 62; E Q

INVENTOR TOM A. BITHER, JR.

ATTORNEY S p 1965 'r. A. EITHER, JR 3 3 MANGANESE. GALLIUM, IRON M NETIC L 01' AND METHOD OF PRODUCING PARTICULAR C TAL ST TURE THEREOF Filed Nov. 22, 1963 5 Sheets-Sheet 2 FIG. II

INVENTOR TOM A. BITHER, JR.

ATTORNEY Sept. 21, 1965 'r. A. BITHER, JR 3 ,633

MANGANESE. GALLIUM, IRON MAGNETIC ALLOY AND METHOD OF PRODUCING PARTICULAR CRYSTAL STRUCTURE THEREOF Filed Nov. 22, 1963 5 Sheets-Sheet 5 FIG. HI

INVENTOR TOM A. BITHER, JR.

ATTORNEY Sept. 21, 1965 T. A. BITHER, JR

MANGANESE, GALLIUM, IRON MAGNETIC ALLOY AND METHOD OF PRODUCING PARTICULAR CRYSTAL STRUCTURE THEREOF 5 Sheets-Sheet 41 Filed Nov. 22, 1963 Gm 5253 2 E3325 95E 08 2 265 Sod 80 25d a G2:

SmI MS 264: 1562 z 3 53 $22 INVENTOR TOM A. BITHER, JR.

ATTORNEY Sept. 21, B965 3,207,633 F PRODUCING T. A. BITHER, JR MANGANESE, GALLIUM, IRON MAGNETIC ALLOY AND METHOD 0 PARTICULAR CRYSTAL STRUCTURE THEREOF 5 Sheets-Sheet 5 Filed Nov. 22, 1963 Sa 55:25; up 2: c

2: 1 com xqurn (S/HHEI) NOllVZIlElNEJVW INVENTOR TOM A. BITHER, JR.

ATTORNEY United States Patent 3,207,638 MANGANESE, GALLIUM, IRON MAGNETIC AL- LOY AND METHOD OF PRODUCING PARTICU- LAR CRYSTAL STRUCTURE THEREUF Tom A. Either, Jr., Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Nov. 22, 1963, Ser. No. 325,675 11 Claims. (Cl. 148-100) This invention relates to new ferromagnetic materials and methods for their preparation. More specifically, the invention is concerned with ferromagnetic manganeseiron-gallium compositions and their preparation.

Various binary alloys are known which are composed of two of the three components of the present invention; however, many of these alloys are nonmagnetic. A few ternary alloys containing manganese, gallium, and one other component have been reported by Hames, J. Applied Phys. 31S, 370 (1960). These compositions, however, are of the L2 (Heusler)-type structure or of the C1 structure, and moreover, have relatively large cell constants of 5.77-5.85 A.

The present invention provides ferromagnetic compositions consisting essentially of 9-56 atom percent manganese, 9-66 atom percent iron, and 19-41 atom percent gallium. These compositions are alloys having a facecentered cubic crystal structure, a hexagonal crystal structure, or a pseudo-cubic crystal structure, depending upon the method of preparation.

FIG. I defines, in graph form, the percent composition of the alloys of the invention having a face-centered cubic crystal structure.

FIG. 11 describes, in graph form, the percent composition of said alloys having a hexagonal crystal structure.

FIG. III shows, in graph form, the percent composition of said alloys having a pseudo-cubic crystal structure.

FIG. IV shows the unusual hysteresis properties of some of the crystal structures of the invention.

FIG. V is a plot of Magnetization vs. Temperature of some of the crystal structures of the invention.

The compositions are prepared by thoroughly mixing manganese, iron, and gallium in the desired proportions, or by mixing one of the components with an alloy of the other two. The mixture, which may be in powder or lump form, is then placed in a non-reactive container, such as an alumina crucible, and heated to a temperature and for a time suflicient to melt the ingredients. This temperature will usually be in the range of 1100 to 1550" C. Most desirably, the mixture is initially heated in a vacuum to remove occluded gases, followed by continued heating in an inert atmosphere such as argon or helium. The pressure of the atmosphere is not critical and may range from 0.5-1.5 atmospheres.

After the mixture becomes completely molten, the heating may be discontinued, for prolonged heating is unnecessary. The molten miXtUre is then allowed to solidify by cooling, and the resulting solid mass may then be annealed if desired.

At gallium contents above 30 atom percent a pseudocubic structure is obtained and special heat treatments need not be employed. However, it is desirable to anneal at a temperature above 725 C., e.g., at 800-850 C. followed by quenching to obtain this structure in the purest form. At gallium contents below 30 atom percent the structure obtained depends upon heat treatment. When the solid mass is annealed at a temperature below 725 C., e.g., at 500700 C., followed by cooling (the rate of which is immaterial), the resulting product has a hexagonal crystal structure. When the solid mass is annealed above 725 C., e.g., at 800850 C., followed by quenching, the product has a face-centered cubic crystal structure. It will of course be understood that small amounts of the other structures described may be present in any of the compositions.

The annealing is conveniently carried out in an evacuated quartz tube, usually for a period of 1-200 hours. Quenching is normally carried out by immersing the hot material in a cold liquid, e.g., ice water, or cold mineral oil.

The magnetic properties of the manganese-iron-gallium compositions depend upon the proportions of the ingredients employed and upon the crystal structure obtained, as discussed below.

FACE-CENTERED CUBIC CRYSTAL STRUCTURE This crystal structure is obtained when the solid mass contains less than 30 atom percent gallium and is annealed at temperatures above 725 C. followed by quenching. The range of total composition making up the total atom percent of the ternary alloys having this crystal structure is depicted in FIG. I by the area enclosed within a, b, c, d, e, f, g, and a. As can be seen in FIG. I, the atom percent limitations are 9-56 atom percent manganese, 14-66 atom percent iron, and 19-30 atom percent gallium. The cubic crystal structure was verified by X-ray analysis and the cell constant determined to be 3.67-3.77 A. The compositions are strongly magnetic and thus find use in coil cores and as permanent magnets.

Some of these face-centered cubic crystals exhibit the property of exchange anisotropy.

This property exists as a result of a magnetic interaction between two regions such as a ferromagnetic region and an antiferrimagnetic region. As shown and described by Meiklejohn and Bean, Phys. Review 105, 904 (1957) and by Meiklejohn, Jour. Applied Phys. 33S, 1328 (1962), the property of exchange anisotropy is evidenced by a shifted hysteresis loop, by a sin 6 torque curve, and by rotational hysteresis. A shifted hysteresis loop is unequivocal evidence of exchange anisotropy.

A shifted hysteresis loop can be found by measurement of the BH loops. Displacement of the loop increases the energy product, i.e., the measure of the potential energy stored in a magnet, and results in an improved permanent magnet. The measure of the increased energy product can be found roughly by observing the area of the (BH) loop. The energy product increase can also be measured by the sin 0 torque curve.

A shifted loop measured at -l96 C. typical of the compositions of face-centered cubic structure, referred to above, is shown in FIG. IV. Other evidence for exchange anisotropy in these compositions is the sin 0 dependence of the torque curve on angle 0 of rotation and the continued presence of rotational hysteresis at fields above 16,000 oersteds. Rotational hysteresis is defined as the integral over 360 of the torque produced when a magnetic material is rotated in a magnetic field. The rotional hysteresis represents that part of the potential energy of the magnetic material in the field converted to thermal energy during rotation.

As a result of the increased energy product, the compositions exhibiting exchange anisotropy result in improved fine particle magnets.

For these products, a broad field dependent maximum occurs in the magnetization over a temperature range. The decrease in the magnetization at low temperatures is believed to be consistent with the appearance of exchange anisotropy. As shown in FIG. V, the two curves labelled I-A indicate that the maximum magnetization varies as either the temperature and/or field strength vary.

In the present products, it is possible that the two regions necessary for exchange anisotropy are those indicated by the two sets of lines in the X-ray pattern. If this theory is correct, the secondary phase of smaller unit cell size probably constitutes an antiferromagnetic region and the principal phase of larger unit cell size is the ferromagnetic region. Both phases have face-centered cubic crystal structure. The cell constant of the principal phase is 3.67-3.77 A.; that of the secondary phase is about 0.3 A. smaller. An alternate explanation is that the anisotropy results from competing localized atomic interactions.

For maximum energy product, i.e., maximum product of magnetization and coercive force, and maximum exchange anisotropy, it is preferred that the compositions contain 24-42 atom percent manganese; 33-48 atom percent iron; 22-28 atom percent gallium; or 23-33 atom percent manganese; 48-52 atom percent iron; and 19-28 atom percent gallium. In FIG. I, the area covered by the foregoing atom percent ranges is denoted by the area included within g, h, i, j, k, l, m, n, f and g.

HEXAGONAL CRYSTAL STRUCTURE Compositions of this crystal structure are obtained by carrying out the annealing step of the novel process below 725 C. upon solids containing less than 30 atom percent gallium. The hexagonal crystal structure has cell constants which range from a:5.21-5.31 A.; :4.23- 4.34 A. Preferred compositions of this crystal structure are manganese, 9-56 atom percent; iron, 14-66 atom percent; and gallium, 19-30 atom percent. This range of atom percent compositions is disclosed in FIG. II as the area enclosed by 0, p, q, r, s, t, u and 0. The structure is also obtained at gallium contents up to 35 atom percent but is mixed with other structures.

Because of maximum magnetic properties, especially preferred compositions of the hexagonal crystal structure are comprised of 9-56 atom percent maganese, 14- 66 atom percent iron, and 22-30 atom percent gallium. The area in FIG. II covered by these especially preferred compositions is within the enclosed area represented by p q, t and P- PSEUDO-CUBIC STRUCTURE Crystals of this type are obtained when the gallium content of the ternary compositions exceeds 30 atom percent, either by direct fusion or preferably when an annealing step is carried out above 725 C. Crystals of this type, as with the other crystal types, exhibit magnetic properties.

Crystals of this type are termed pseudo-cubic herein because the X-ray work carried out to date is insufficient to distinguish unequivocally between a cubic and a slightly canted cubic or rhombohedral structure. The cell constant for a cubic crystal of this type has been determined to be 8.7-9.0 A.; however, it is possible that this structure may be rhombohedral with cell constants, a=8.7-9.0 A. and a:889().

The atom percent limitations of the pseudo-cubic crystal compositions are 9-56 atom percent manganese, 9-61 4% atom percent iron and 30-41 atom percent gallium. This range is exemplified in FIG. III by the area included within v, w, x, y, z and v.

The examples below are illustrative of this invention. In these examples commercially available materials are employed and quantities are given in parts by weight except as noted. The magnetic properties described are the magnetic moment per gram (emu/ g.) measured in fields of 2 and 15.75 koe., the Curie temperature, and the intrinsic coercive force, H These properties are described in Ferromagnetism by Bozorth, D. Van Nostrand Co., Inc., New York, 1951, pp. 5-8. The valves of magnetic moment given herein are determined on apparatus similar to that described by T. R. Bardell on pp. 226-228 of Magnetic Materials in the Electric Industry, Philosophical Library, New York, 1955. Values for coercive force herein and B-H loop measurements are determined on a DC. ballistic-type apparatus which is a modified form of the apparatus described by Davis and Hartenheim in the Review of Scientific Instruments, 7, 147 (1936). The Curie temperature, T is determined from measurements of the magnetic moment at various temperatures in a 15.75 koe. field. Rotational hysteresis and torque measurements are described by Meiklejohn and Bean, Physical Rev. 105, 904-913 (1957) and the apparatus used in torque measurements is described by Crawford, J. Appl. Phys. 29, 493 (1958). X-ray powder patterns were obtained on film from filings passing a 200 mesh screen (US. Standard Sieve series) using cobalt K, radiation. The filings (sealed in evacuated quartz tubes) were annealed under the temperature conditions listed in the following examples before X-ray patterns were taken.

Example 1 This example illustrates the preparation of manganeseiron-gallium compositions having cubic crystal structure and exhibiting exchange anisotropy.

A. A mixture of powdered manganese, iron and small pieces of gallium in the proportions on an atomic basis of 40:35:25 was placed in an aluminum oxide crucible and heated in a carbon resistance furnace. The whole assembly was enclosed by a bell jar which was evacuated during the initial stages of the heating, i.e., up to a temperature of about 600 C. Thereafter argon was admitted to the bell jar to a pressure of about 0.5 atmosphere and the temperature of the furnace was increased sutficiently to cause the mixture to melt (about 1425 C.). The mixture was maintained in the molten condition for 14 minutes after which the temperature was reduced over a period of about 10 minutes to about 300 C., the power to the furnace was turned off, the crucible was removed from the furnace, and the solidified melt removed. The pgdut was magnetic with a Curie temperature at about A portion of the product was annealed by heating at 800 C. for 142 hours and was then quenched by plunging into ice water. This annealed and quenched product exhibited an X-ray diffraction pattern which was indexed on the basis of a face-centered cubic structure with a cell constant of 3.740 A. Two extra weak lines in the pattern corresponded to a second face-centered cubic structure with a cell constant of 3.450 A. as illustrated more fully in Example 1-B.

The magnetization of the annealed and quenched material was measured as a function of temperature with the results shown in FIG. V. A field dependent maximum (evidenced by the two curves labelled I-A) occurs in the magnetization. Measurements of B-H loops were carried out at room temperature and at -196 C., after cooling in a field, as indicated in FIG. IV. A symmetrical loop was observed at room temperature, but after cycling at -196 C. the loop was displaced demonstrating the presence of exchange anisotropy. The coercive force of the annealed and quenched product, cooled to -196 C. in the absence of a field, was 700 7 It will be noted that a field dependent maximum in the gallium compositions of cubic crystal structure. Compositions were prepared by the general procedure of Example 1. Composition, temperature of maximum magnetization, Curie temperature and cell constants for these products are given in Table II, below.

TABLE II.FACE-CENTERED CUBIC MANGANESE-IRON-GALLIUM COMPOSITIONS Composi- Face-Centered Example tron (Atom Fusion T Ts Cubic Structure N 0. Percent) Tempera- 0.) 0.) Cell Constant Ga ture, C. (A.) Mn Fe 45 35 1,500 68 3. 706 (3. 42) 40 40 20 l, 500 50 3. 696 (3. 42) 30 50 20 1, 370 3. 687 (3.405) 55 20 1,380 3. 734 (3.453) 45 25 1, 485 3.716 (3.430) 30 25 1, 460 3.720 (3. 44) 25 25 1, 470 3.700 (3.47) 20 25 1, 445 3. 692 10 l 25 3. 703 40 30 3O 1, 500 3. (3. 45) 30 40 30 1, 490 3. 726

15,750 oersteds.

The presence of high internal fields in the product was also indicated by rotational hysteresis measurements carried out as a function of field strength at room temperature (where the usual curve was obtained) and at 196 C. (where the effect of rotational hysteresis was observed at high magnetic fields).

B. A mixture of manganese-iron-gallium composition in the proportions on atomic basis of 35:40:25 was treated in the manner described above (the molten condition occurred at about 1385 C. and was maintained 5 minutes) to yield a magnetic product having a Curie temperature of 400 C. This product was annealed as described above and quenched into ice water. The annealed and quenched product gave an X-ray diffraction pattern which was indexed on the basis of a face-centered cubic structure having a cell constant of 3.716 A. A second, weaker pattern was also present that corresponded to a face-centered cubic structure having a cell constant of 3.430 A. The X-ray pattern of this annealed product is tabulated below in Table I.

TABLE I.-X-RAY PATTERN OF MANGANESE-IRON- GALLIUM COMPOSITION OF FACE'CENTERED CUBIC STRUCTURE Example 13 This example illustrates the preparation of magnetic manganese-iron-gallium compositions having hexagonal crystal structure.

A. A mixture of manganese, iron and gallium in the proportions on atomic basis of 40:35:25 was melted and cooled as described in Example 1-A. A portion of the product was annealed by heating at 678 C. for 120 hours and then quenched into ice water. The X-ray difiraction pattern of the annealed and quenched product corresponded to a hexagonal crystal structurehaving the cell constants: a, 5.276 A.; c, 4.279 A. This X-ray diffraction pattern is given below in Table III.

TABLE IiII.-X R AY PATTERN 01 MANGA-NESE DR'O N- GALLI UlM lC OMFPlOlS ITlIO'N IOF H'EXAGONA L CRYSTAL STRUCTURE Miller Indices (h k 1) Face- Centered Cubic Structures Intensity 1 d Spacing (A.)

a, 3.716 A. a, 3.43 O A.

1 Sindicates a strong line, M-a line of intermediate intensity, and V-a weak line.

Measurements of magnetization as a function of temperature were made as described above and the results are included in FIG. V in the two curves labelled I-B.

magnetization was observed. Rotational hysteresis was also measured and as with the observation made upon the sample obtained in I-A indicated the presence of high internal fields. The annealed and quenched product had a coercive force at 196 C. of approximately 1325 oersteds and exhibited a displaced B-H loop at this temperature.

Examples 2-12 These examples illustrate various manganese-iron- Miller Indices (h kl) Intensity 1 d Spacing (A.) Hexagonal Structure,

a, 5.276 A.; c, 4.279 A.

1 S-indicates a strong line, M-indicates a line of intermediate intensity and V-indicates a weak line.

The magnetization of the annealed product was measured as a function of temperature in a field of 15.75 kilooersteds. A normal magnetization curve was obtained, the magnetization at l C. being 57 emu/ g. and at 25 C. 35 emu/g. The Curie point was 143 C.

B. A mixture of manganese, iron and gallium in the proportions on an atomic basis of 35:40:25 was melted and cooled as described in Example 1-B. A portion of the product was annealed by heating at 678 C. for hours and quenched into ice water. The annealed and quenched product gave an X-ray diffraction pattern that corresponded to a hexagonal structure with cell constants: a, 5.268 A.; c, 4.268 A. The product gave a normal magnetization curve with a magnetization at C. of 87 emu/g. and at 25 C. of 66 emu/g. (measured in a 15.75 koe. field). The Curie temperature was 197 C.

Examples 14-22 These examples illustrate various manganese-iron-gallium compositions of hexagonal crystal structure. The compositions were prepared by the general procedure of Example 13. Composition, Curie temperature and cell constants for these products are given below in Table IV.

TABLE IV.HEXAGONAL MANGANESE-IRON-GALLIUM COMPOSITIONS Composition Hexagonal Cell (atom percent) Fusion '1. Constants (A.) Example No. Tempera- C.)

ture Mn Fe Ga 8. c

Magnetization measured in a 15,750 oersted field at 25 C. was 101 emu/g. for the product of Example 18 and 126 emu/g. for the product of Example 20.

Example 23 This example illustrates the preparation of a manganeseiron-gallium composition having a pseudo-cubic crystal structure.

A mixture of manganese, iron and gallium in the pro portions on atomic basis of 30:30:40 was melted by heating as described in Example 1 at approximately 1275 C. for 8 minutes and cooled. The product was annealed at 850 C. for 96 hours and quenched into ice water. The annealed and quenched product had an X-ray pattern corresponding to a pseudo-cubic crystal structure with a cell constant of 8.87 A. Two additional lines were indexed on the basis of the face-centered cubic structure described in Example 1. The X-ray pattern is given below in Table V.

Miller Indices (h k l) Intensity 1 d Spacing (A.)

Face-Centered Cubic Structure Pseudocubic Structure 1 S-indicates a strong line, M-indicates a line of intermediate intensity, and V-indicates a weak line.

The product showed a normal magnetization-temperature curve (measured in a field of 15.75 kilooersteds) with a magnetization at -195 C. of 83 emu/ g. and at 25 C. of 65 emu/ g. The Curie temperature was 255 C. A second preparation annealed at 600 C. and slowly cooled to room temperature had a Curie temperature of 250 C.

Examples 24-28 These examples illustrate various manganese-iron-galliurn compositions of pseudo-cubic crystal structure. Compositions were prepared by the general procedure of Example 23 with the exception of Example 26 (see below). Composition, Curie temperature and cell constants for these products are given in Table VI.

The composition of Example 26 was placed in an alumina crucible contained in an outer quartz tube and heated in a muffle furnace. The composition was outgassed under vacuum at 300 C. for 16 hours and then placed under argon gas at atmospheric pressure. This pressure was maintained while the composition was fused by heating to 1150 C. over a period of 5.5 hours and holding at this temperature for 1.25 hours. The composition was cooled to 800 C. over a period of 1.75 hours and the furnace was then turned oil to allow the composition to cool more rapidly to room temperature. The product was a metallic slug which was magnetic at room temperature.

TABLE VI.-PSEUDO-CUBIC MANGAN ESE-IRON-GALLIUM COMPOSITIONS Composition (Atom percent) To Pseudo-cubic Example N 0. C.) Cell (8x13560111;

Mn Fe Ga Magnetization measured at 25 C. in a field of 15,750 oersteds was 78 emu/g.

The compositions of this invention have widely varying magnetic properties and thus their application is dependent on the particular material prepared. Certain of these materials find application in the electronics industry where a moderate energy product is desired. Such materials include the compositions prepared from the hexagonal and pseudo-cubic crystal structured compositions. They can also be used in preparing coil cores and permanent magnets.

The materials having a face-centered cubic crystal structure can be used in the applications described in the foregoing paragraph. The materials exhibiting exchange anisotropy make excellent permanent magnet material due to the high energy product of the material. These materials are also suitable for applications requiring a strongly magnetic material at low temperatures.

All of the compositions can be fabricated into permanent magnets of intricate shape suitable for a particular use by grinding them to powder, followed by fabrication into varying shapes by powder metallurgy techniques.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not limited to the specific embodiments thereof except as defined in the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A magnetic composition consisting essentially of 9-56 atom percent manganese, 9-66 atom percent iron, and 19-41 atom percent gallium.

2. A magnetic composition having a face-centered cubic crystal structure and consisting essentially of 9-56 atom percent manganese, 14-66 atom percent iron, and 19-30 atom percent gallium.

3. A magnetic composition having a face-centered cubic crystal structure consisting essentially of 24-42 atom percent manganese, 33-48 atom percent iron, 22-28 atom percent gallium, and 23-33 atom percent manganese, 48-52 atom percent iron, and 19-28 atom percent gallium; the above range of total composition being defined by the area enclosed within the points g, h, i, i, k, l, m, n, f, and g of FIG. I.

4. A magnetic composition having a hexagonal crystal structure consisting essentially of 9-56 atom percent manganese, 14-66 atom percent iron, and 22-30 atom percent gallium.

5. A magnetic composition having a hexagonal crystal structure consisting essentially of 9-56 atom percent manganese, 14-66 atom percent iron, and 22-30 atomo percent gallium.

6; A magnetic composition having a pseudo-cubic crystal structure consisting essentially of 9-56 atom percent ganese, 14-66 atom percent iron, and 22-30 atom percent gallium 7. A magnetic composition having a face-centered cubic crystal structure consisting essentially of 40 atom percent manganese, 35 atom percent iron, and 25 atom percent gallium.

8. A magnetic composition having a hexagonal crystal structure consisting essentially of 35 atom percent manganese, 40 atom percent iron, and 25 atom percent gallium.

9. In the process for preparing an alloy by heating a mixture containing elements to melting temperature in an inert atmosphere followed by cooling the molten mixture to solidification, the steps which comprise annealing a cooled composition of 9-56 atom percent manganese, 14-66 atom percent iron and 19-30 atom percent gallium at a temperature above 725 C. and quenching to produce face-centered cubic crystals of said composition.

10. In the process of preparing an alloy by heating a mixture containing elements to melting temperature in an inert atmosphere followed by cooling to solidification, the steps which comprise annealing a cooled composition of 9-56 atom percent manganese, 14-66 atom per cent iron and 19-30 atom percent gallium at a temperature below 725 0, followed by cooling to produce hexagonal crystals of said composition.

11. In the process for preparing an alloy by heating a mixture containing elements to melting temperature in an inert atmosphere followed by cooling to solidification, the steps which comprise annealing a cooled composition of 9-56 atom percent manganese, 9-61 atom percent iron and -41 atom percent gallium at a temperature above 725 C., and quenching to produce pseudo-cubic crystals of said composition.

References Cited by the Examiner UNITED STATES PATENTS 2,961,360 11/60 Kouvel et a1 148100 2,982,678 5/61 Howe 148-100 OTHER REFERENCES Tsuboya et al., article in Journal of the Phys. Soc. of Japan, vol. 18, No. 1, January 1963, page: 143.

DAVID L. RECK, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 207 ,638 September 21, 196

Tom A. Bither, Jr.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 12, for "valves" read values column 5, TABLE I, sub-heading to the last column thereof, for "a, 3.43 0 A." read a, 3.430 A. column 6, TABLE II,

headings to the second and third columns thereof, for

Composition (Atom Composition (Atom Percent) Percent) riead Ga Mn Fe Mn #Fe Ga column 8, line 74, for "22-30" read 19-30 column 9, line 3, for "atomo" read atom line 7, for "14-66 atom percent iron, and 22-30" read 9-61 atom percent iron, and 30-41 Signed and sealed this 3rd day of May 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A MAGNETIC COMPOSITION CONSISTING ESSENTIALLY OF 9-56 ATOM PERCENT MANGANESE, 9-66 ATOM PERCENT IRON, AND 19-41 ATOM PERCENT GALLIUM. 